The Klassik Open Air & Feuerwerk is the traditional climax of the Ludwigsburg Festival, which sees up to eight thousand music lovers enjoy classical sounds in an informal open air environment. Each summer the event, held at the idyllic Monrepos Palace, closes with a spectacular firework display. In 2018, under the headline ‘flames of passion’ the orchestra performed works by Wagner, Gershwin, Rimsky-Korsakow, Bizet, Ravel, and others – with castanets and fiery rhythms from the flamenco to the fandango.

Providing sound reinforcement was the KSL System, the latest addition to the d&b SL-Series. The Klassik Open Air & Feuerwerk is a traditional test location for d&b. Almost any time there is something new from d&b, the company heads to the Palace.

The site required an elongated flat surface to be filled with sound. The entire distance to be covered totals around one hundred and fifty meters; the seated front section comprises six thousand five hundred seats across a length of around ninety meters.

Nine KSL8 and three KSL12 loudspeakers were utilized either side of the stage, with four d&b Y7Ps employed as nearfill. Ten V-SUB double stacks were distributed at ground level at the front edge of the stage and operated as a virtually curved SUB array. This seemingly remarkable number of subwoofers for a classical context served less for reaching high sound pressure levels and more to achieve a particularly uniform distribution of low frequencies.

Behind the stage Monrepos Palace forms a charming, if not problematic architectural backdrop, at least from an acoustic perspective; the concave curve of the castle’s baroque facade creates disruptive reflections especially in the lower midrange. With KSL these unwanted reflections were significantly reduced leading to an even cleaner sound than previous years. The contours of the low mids were reproduced in a more defined way, and for instruments such as double bass, viola, and cello, more gain before feedback was achieved.

With the help of ArrayProcessing the sonic results were such that, over the seated area, a moderate level drop of just 2.5 dB per doubling of distance was achieved. In the picnic area on the hill, a powerful level drop was set. The beam was set up in such a way that it was ‘shot’ a little above the rearmost seats, which provided buffers for evening air movements and a possible atmospheric inversion. The available headroom was used to ensure as uniform a frequency response as possible, which could be heard a long way back on the square. Varying temperatures and humidity values could be tracked using the d&b ArraySight inclinometers mounted on the KSL Flying frames – these sent these data, via the OCA/AES70 protocol, to the d&b R1 Remote control software at FoH with any necessary adjustments to the system made via ArrayProcessing.

Matthias Reusch is responsible for the sound mix at Klassik Open Air & Feuerwerk and is considered ‘the man with the golden ears’ in specialist circles. He has worked at the event for the past eighteen years. “So far, everything that d&b has employed has been a huge improvement. In 2013 ArrayProcessing, in its absolute beta stage, was tested for the very first time at the Klassik Open Air & Feuerwerk. For me, this was the squaring of the circle – for the first time, we had a great sounding system whose sound no longer changed across the distance, warmth even in the rear areas, and no appreciable level decay – this didn’t exist before. With ArrayProcessing we’re throwing it out across a distance of nearly one hundred and fifty meters, without a delay, and even right at the back, the system is present in a really desirable form. It was actually perfect.

“Now, with KSL’s broadband directivity control the bar has indeed been raised once again. With these loudspeakers we have a significantly quieter stage this year due to the distinct backward damping. My impression is that, in 2018, we achieved the same sound pattern as in previous years with less total volume – we are quieter, but despite this, I’m perceiving the same intensity. We work on the Soundcraft Vi6 console with a file that has grown over the years – and, in this respect, there is good comparability.”

Martin Würfele from Neumann&Müller the event technology specialists equipping both sound and light, has been project manager since 2006. “The Klassik Open Air & Feuerwerk is a lovely concert in a wonderful setting and with a great atmosphere – it is quite simply fun to work here,” he commented. “The approach of supplementing the main sound system with surround loudspeakers fitted to the side of the seated areas has been a success for years. With the development of ArrayProcessing, we have, for several years, been able to dispense with an additional delay line, which used to provide sound for the hill where those with picnic tickets are located. KSL has significantly improved the sound again – the same even sound pattern is produced across the entire required area. At the Klassik Open Air & Feuerwerk, we have been trying out new things for years and, to this day, we have had nothing but good experiences with the new products from d&b.”